Children coming into contact with child welfare agencies constitute what has been described as the dominant public mental health problem when it comes to children. These approximately 5.8 million children are disproportionately non-white, and display considerable race/ethnic disparities in their utilization of mental health services. What makes these disparities especially pernicious is that virtually all of these children have entitlements to Medicaid. Medicaid agencies' ability to reduce these disparities occurring among its beneficiaries is hampered by the lack of information on what factors result in differential utilization of services among children of different race/ethnicities, which has the potential risk of worsening mental health outcomes among this highly vulnerable population. For the first time in the field of child welfare research, members of this research team are assembling a unique data set that links the respondents of a national survey of children in child welfare to their Medicaid claims data, along with information on Medicaid and mental health policies within their counties of residence. Such a linkage combines the richness of person-level information contained in survey data - such as need for mental health services identified using standardized psychometric measures - with the use and expenditure information contained in claims data. In the present study, we propose to complete construction of this data set, and then conduct longitudinal data analysis to (1) model race/ethnic differences in mental health service utilization (ambulatory mental health service use, inpatient hospitalizations, psychotropic medication use, overall service volume, and timeliness of services) and expenditures among a national sample of children in child welfare; (2) estimate race/ethnic differences in mental health services utilization and expenditure trajectories over the childhood development cycle (ages 0- 18 years) among these children; and (3) examine the role of care consistent with national standards as mediators of race/ethnic differences in mental health service utilization and expenditures (from Aim 1), and use and expenditure trajectories (from Aim 2), among these children; and (4) effects of Medicaid policies (presumptive eligibility, managed care, and system coordination) on race/ethnic differences in mental health service utilization and expenditures (from Aim 1), and use and expenditure trajectories (from Aim 2), among these children This proposal by a new investigator brings together a highly experienced team of senior investigators and a state Medicaid policymaker to address these salient issues with respect to Medicaid coverage of a very vulnerable child population. This proposal is aligned to several Federal and NIH priorities, including the NIMH Strategic Plan, several reports of the Surgeon-General, publications from the Institute of Medicine, and several of the proposed objectives from Healthy People 2020, all of which call for policy action that can reduce and eliminate disparities in mental health.